Effects of GABA Modulator AZD7325 on Cortical Excitability

Healthy Clinical Trial

Official title: A Phase I Single Site, Single Dose, Randomised, Double-blind, Placebo Controlled 3-way Cross-over Biomarker Study Investigating the Effect of the GABA Modulator AZD7325 on Short Interval Intracortical Inhibition (SICI) in Healthy Volunteers

Status Completed

Clinical Trial Summary

GABA (gamma-aminobutyric acid) is the main inhibitory compound in the human brain. Drugs that enhance its effects by binding on GABA receptors (e.g., benzodiazepines) are used to treat various diseases such as epilepsy, insomnia, anxiety or movement disorders. However, the use of these medications is often compromised due to their side effects, like sedation, cognitive impairment, and addiction.

Many of these side effects have been linked to a particular type of GABA receptor (GABA A alpha 1). Therefore, effort is being made to develop drugs that do not act on this receptor, but maintain their beneficial properties by acting on other types of GABA receptors. AZD7325 is a drug that selectively acts on GABA A alpha 2 and A alpha 3 receptors, but not A alpha

1. It has been tested in more than 700 people and so far proved to be generally well tolerated. Positron emission tomography (PET) study in humans demonstrated that AZD7325 binds to GABA A receptors in the brain after a single dose. Early clinical studies have shown that it has less sedative and cognitive adverse events as compared with a benzodiazepine lorazepam.

In this study, we will investigate its effects on short interval intracortical inhibition (SICI). SICI is neurophysiological marker of inhibitory processes in the motor cortex. It is obtained non-invasively by using transcranial magnetic stimulation (TMS). In TMS, magnetic impulses applied over the scalp that in turn induce a current in a small area of the brain. If applied over the motor areas of the brain, impulses result in muscle twitch that is recorded with surface electrodes. SICI is enhanced by certain drugs like benzodiazepines that act on GABA A alpha 1,2,3, and 5 receptor subtypes, but not by zolpidem acting solely on alpha 1 subtype. Because GABA A alpha 5 receptor subtype is less common in the cortex, it has been concluded that the drug effects on SICI are related to GABA A alpha 2 and alpha 3 receptors.

If AZD7325 proves to enhance SICI in healthy volunteers, this would create the grounds for the use of this medication to treat certain neurological disorders in which SICI has been found to be impaired (e.g., dystonia).

Clinical Trial Description

n/a

Study Design

Allocation: Randomized, Endpoint Classification: Pharmacodynamics Study, Intervention Model: Crossover Assignment, Masking: Double Blind (Subject, Investigator), Primary Purpose: Basic Science

Related Conditions & MeSH terms

• Healthy

• NCT number: NCT02135198
• Study type: Interventional
• Source: University College, London
• Status: Completed
• Phase: Phase 1
• Start date: September 2014
• Completion date: August 2015